Unit 1 Section 2 The Crime Scene

Physical Evidence Any and all objects that can establish a crime has been committed or can link a crime and its victim to its perpetrator. Any and all objects that can establish a crime has been committed or can link a crime and its victim to its perpetrator. You have to know what to look for and what to collect You have to know what to look for and what to collect Only those things that the lab can test or examine should be collected Only those things that the lab can test or examine should be collected If you collected everything the lab would be overflowing with samples. If you collected everything the lab would be overflowing with samples.

People are specifically trained to collect crime scene evidence that is useful and to collect it in a specific way so that the sample is not damaged. People are specifically trained to collect crime scene evidence that is useful and to collect it in a specific way so that the sample is not damaged.

Securing and Recording the Crime Scene Evidence must be observed and recorded in its original condition Evidence must be observed and recorded in its original condition First officer at a crime scene must secure and protect the area First officer at a crime scene must secure and protect the area Ropes or barricades are used along with guards Ropes or barricades are used along with guards Everyone who enters the crime scene can destroy evidence Everyone who enters the crime scene can destroy evidence

Lead investigator determines the boundaries of the scene Lead investigator determines the boundaries of the scene Then determines how the perpetrator entered and exited the scene Then determines how the perpetrator entered and exited the scene Obvious crime-scene evidence is documented and photographed Obvious crime-scene evidence is documented and photographed A walk-through of the scene is done to get an overview of the situation and develops a strategy of how to examine and document the crime scene. A walk-through of the scene is done to get an overview of the situation and develops a strategy of how to examine and document the crime scene.

Record the Scene Records are used to investigate the crime and during trial Records are used to investigate the crime and during trial Three methods for crime scene recording: Three methods for crime scene recording: 1.Photography 2.Sketches 3.Notes

Photography Objects cannot be moved until they are photographed from all angles or they may not be useful during a trial Objects cannot be moved until they are photographed from all angles or they may not be useful during a trial Crime scene is photographed along with all surrounding areas and points of exit and entry Crime scene is photographed along with all surrounding areas and points of exit and entry If there is a body it must be photographed to determine its location in the room If there is a body it must be photographed to determine its location in the room Close-ups of items are taken as well Close-ups of items are taken as well Sometimes a ruler is used to reference size Sometimes a ruler is used to reference size

Sketches Rough sketch – contains an accurate depiction of the dimensions of the scene and shows the location of all objects having a bearing on the case. Rough sketch – contains an accurate depiction of the dimensions of the scene and shows the location of all objects having a bearing on the case. Distance measurements are used to place items in the room Distance measurements are used to place items in the room Items in the room are represented by letters Items in the room are represented by letters A legend is used to designate the items in the sketch A legend is used to designate the items in the sketch Should have a heading facing north Should have a heading facing north

Finished sketch – looks nicer and reflects information contained within in the rough sketch so it can be used in court. Finished sketch – looks nicer and reflects information contained within in the rough sketch so it can be used in court. Computer-aided drafting is the standard method for reconstructing crime scenes from rough sketches Computer-aided drafting is the standard method for reconstructing crime scenes from rough sketches

Notes Includes: Includes: –Detailed written description of the scene –Location of the types of physical evidence recovered –Time evidence was discovered, by whom, how and by whom it was packaged and marked, and condition of the item after it was collected. You can tape record the notes You can tape record the notes Must be detailed enough to refresh someone’s memory months or years later Must be detailed enough to refresh someone’s memory months or years later Can use videotape but it must be written down later. Can use videotape but it must be written down later.

Dealing with Physical Evidence Specific procedures for finding, collecting and transporting physical evidence so that it can be compared and analyzed in a forensic lab. Specific procedures for finding, collecting and transporting physical evidence so that it can be compared and analyzed in a forensic lab.

Searching For Evidence Must be thorough and systematic Must be thorough and systematic Not done by a forensic scientist but usually by trained technicians like CSI Not done by a forensic scientist but usually by trained technicians like CSI Search depends on location and size of area as well as actions of suspects and victims Search depends on location and size of area as well as actions of suspects and victims Should have one person in charge to organize the search Should have one person in charge to organize the search Several types of crime scene search patterns Several types of crime scene search patterns Search must include entry and exit areas Search must include entry and exit areas

Figure 2–7 Several typical examples of crime-scene search patterns. The pattern selected normally depends on the size and locale of the scene and the number of collectors participating in the search.

What they search for depends on the crime What they search for depends on the crime –Homicide: weapon, contact between victim and assailant such as hair, fibers, and blood –Burglary: tool marks on entry point, latent fingerprints –Hit and run: outside and undercarriage of car looking for blood, tissue, hair, fibers, and fabric impressions –Kidnapping: all areas of vehicle are searched

Collecting the Evidence Important to collect large pieces of evidence as well as item that may have trace evidence on them Important to collect large pieces of evidence as well as item that may have trace evidence on them Critical areas should be vacuumed and sent to the lab for analysis Critical areas should be vacuumed and sent to the lab for analysis Fingernail scrapings from individuals can link victims to assailants Fingernail scrapings from individuals can link victims to assailants

Chain of Custody Every person who handled or examined the evidence must be accounted for when the evidence is presented in court. Every person who handled or examined the evidence must be accounted for when the evidence is presented in court. Standard procedure: Standard procedure: Record location of evidence Record location of evidence Mark evidence for identification Mark evidence for identification Properly completing evidence submission forms for laboratory analysis Properly completing evidence submission forms for laboratory analysis

Collectors initials Collectors initials Date of collection Date of collection Location of item Location of item Transfer of materials to a new person requires them to fill out a form Transfer of materials to a new person requires them to fill out a form

Standards and Reference Samples Physical evidence whose origin is known, such as blood or hair from a suspect, that can be compared to crime-scene evidence. Physical evidence whose origin is known, such as blood or hair from a suspect, that can be compared to crime-scene evidence. Buccal swab – swab the inner portion of the cheek to collect cells for DNA profiling. Buccal swab – swab the inner portion of the cheek to collect cells for DNA profiling. –Done for everyone who is relevant to the crime scene

Substrate control – uncontaminated surface material close to an area where physical evidence was found. Used to eliminate the regular material found in that area does not interfere with the laboratory test. Substrate control – uncontaminated surface material close to an area where physical evidence was found. Used to eliminate the regular material found in that area does not interfere with the laboratory test. Used for arson cases and collection of blood stains Used for arson cases and collection of blood stains

Submit evidence to Laboratory In person or by mail In person or by mail Must complete an evidence submission form, includes: Must complete an evidence submission form, includes: –Description of case history will help for comparisons and looking for trace evidence –The kind of examination each piece of evidence should get –List of items submitted for examination

Death and Autopsies The dead body of a victim can be one of the most important pieces of evidence The dead body of a victim can be one of the most important pieces of evidence The body is treated just like all the other evidence The body is treated just like all the other evidence Forensic pathologists examine the body’s anatomy, tissues, blood, organs etc. to determine a cause of death Forensic pathologists examine the body’s anatomy, tissues, blood, organs etc. to determine a cause of death

Forensics Pathologists Must Answer Who is the victim? Who is the victim? What injuries are present? What injuries are present? When did the injuries occur? When did the injuries occur? Why and how were the injuries produced? Why and how were the injuries produced? How did this person die? How did this person die?

Autopsy If observation cannot determine cause of death an autopsy is performed If observation cannot determine cause of death an autopsy is performed Autopsy – medical dissection and examination of a body in order to determine the cause of death. Autopsy – medical dissection and examination of a body in order to determine the cause of death. Five classifications for cause of death Five classifications for cause of death 1.Natural 2.Homicide 3.Suicide 4.Accident 5.Undetermined

Estimating Time of Death Several stages of decomposition after death Several stages of decomposition after death Medical examiner can determine time of death by observing which stage of decomposition the body is in. Medical examiner can determine time of death by observing which stage of decomposition the body is in. Rigor mortis – occurs between the first 24 and 36 hours of death. Muscles stiffen and the body becomes rigid. Rigor mortis – occurs between the first 24 and 36 hours of death. Muscles stiffen and the body becomes rigid. Livor mortis – settling of blood in areas of the body closest to the ground. The skin appears dark blue or purple in this area Livor mortis – settling of blood in areas of the body closest to the ground. The skin appears dark blue or purple in this area Algor mortis – body temperature cools until it reaches room temperature Algor mortis – body temperature cools until it reaches room temperature –Can be affected by size and location of body, victims clothing, weather conditions –Body loses heat at a rate of degrees Fahrenheit per hour until it reaches room temperature

Determining potassium levels in ocular fluid can also be helpful in estimating time of death. Determining potassium levels in ocular fluid can also be helpful in estimating time of death. –Potassium is released from the cells after death so amount of potassium can tell you how long they have been dead Amount of food in the stomach can be used to determine when that person ate their last meal. Amount of food in the stomach can be used to determine when that person ate their last meal.

Evidence during Autopsy Victim is examined to determine cause or manner of death Victim is examined to determine cause or manner of death Tissues and organs are examined for abnormalities and toxins Tissues and organs are examined for abnormalities and toxins Coroner will send the following items to the forensic lab: Coroner will send the following items to the forensic lab: Victim’s clothing Fingernail scrapings Head and pubic hair Blood (DNA) Vaginal, anal, and oral swabs (sex crimes) Recovered bullets from body Hand swabs from shooting victims

Collected evidence must be protected from any changes. Collected evidence must be protected from any changes. Changes can occur through: Changes can occur through: Contamination Contamination Breakage Breakage Evaporation Evaporation Accidental scratching Accidental scratching Bending Bending Or it can be lost all together Or it can be lost all together Evidence should be kept in original condition unless it is attached to a large or unmovable object Evidence should be kept in original condition unless it is attached to a large or unmovable object –Example: Deliver the whole shirt to the lab not just the hair found on the shirt

Each item is placed in a separate container which prevents damage or cross contamination Each item is placed in a separate container which prevents damage or cross contamination Some tools that are used: Some tools that are used: Forceps (tweezers) Forceps (tweezers) Unbreakable plastic pill bottles (hair/fibers) Unbreakable plastic pill bottles (hair/fibers) Manila envelopes, screw cap glass vials, cardboard pill boxes, folded paper, sealable plastic bag (trace evidence) Manila envelopes, screw cap glass vials, cardboard pill boxes, folded paper, sealable plastic bag (trace evidence) Paper bags for clothing prevents mold from growing which can destroy DNA samples Paper bags for clothing prevents mold from growing which can destroy DNA samples Charred debris should be stored in airtight containers to keep petroleum from evaporating (new paint cans/tightly sealed jars) Charred debris should be stored in airtight containers to keep petroleum from evaporating (new paint cans/tightly sealed jars)

Forensic Entomology The study of insects and their relation to a criminal investigation. The study of insects and their relation to a criminal investigation. Used to estimate time of death Used to estimate time of death Blowflies are some of the first to infest the body Blowflies are some of the first to infest the body –Usually within the first hour of death –Lay their eggs in moist areas of the corpse: nose, mouth, armpit, groin, and open wounds. –Lay eggs that hatch into maggots or fly larvae which eat human organs and tissue –For 6-10 days larvae feed, grow, and molt to become pupae

–Day 2: 5mm –Day 5: 17mm –Day 6-8: 12mm –Use length to determine time 12 days later adult flies emerge and the cycle continues 12 days later adult flies emerge and the cycle continues Entomologists can determine how long the person has been dead by the stage of the life cycle the fly is in Entomologists can determine how long the person has been dead by the stage of the life cycle the fly is in –Only eggs – less than 24 hours earlier –Fully grown maggots but no pupae – less then 10 days ago –Pupae – 6 – 10 or more days have passed –Adult flies – two to three weeks earlier ***See page 62 for life cycle

Types of flies found can help determine if the victim was killed at night or during the day Types of flies found can help determine if the victim was killed at night or during the day –Some lay eggs in sunlight, some in the shade –Some types are found in the cold while others are found in the warm weather.

Factors that effect entomology Development can be affected by the weather Development can be affected by the weather Cold weather: blowflies are less common, maggots can go dormant for extended periods of time Cold weather: blowflies are less common, maggots can go dormant for extended periods of time Warm weather: egg laying can occur faster Warm weather: egg laying can occur faster A meteorologist may be consulted A meteorologist may be consulted Can only provide a minimum time Can only provide a minimum time –Example: Pupae cannot appear in fewer then six days New generations of pupae can affect your results New generations of pupae can affect your results –Specimens are collected to observe the type of insects present, their stage of development, and how many development cycles have occurred.